Stern's Birthday Party is actually a Stern Audition for Sirius

Sirius has Stern over the barrel. Sirius knows that Stern's listening base has deteriorated. Stern's contract is up next year. Sirius informs Stern that they will broadcast free of charge his "birthday bash" This will allow Sirius to track how many people listen to the event and, more importantly, how many non-subscribers will subscribe after the event so that they can listen to Stern.

You can tell by the puff pieces written that Stern and Buchwald are dripping flop sweat. I'd be amazed if Stern is offered more than $35 Million come contract time